There were 55 delegates at the 1787 Constitutional Convention. They all made contributions, but the final form of the document was the work of James Madison. Who also wrote the Bill of Rights. Madison was strongly influenced by the Enlightenment philosophy, especially that of John Locke. As regards government and religion, Madison was a very strict separationist. Who opposed not only a publicly paid Congressional chaplain, but also paid chaplains for the military. He (along with Oliver Ellsworth of Connecticut) were major supporters of the no religious test clause in Article VI. Even though some states had laws establishing a state religion for a while, these were gone in the 19th century. And state laws requiring office holders to swear or affirm a belief in God were also voided by SCOTUS, based on Article VI.
These all reflect liberal thinking of the Enlightenment. But Biblical values were also incorporated. The Constitution did not eliminate the ancient practice of one man owning another as a slave.